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1 | /* |
2 | * Common code between the AC-3 encoder and decoder | |
3 | * Copyright (c) 2000, 2001, 2002 Fabrice Bellard | |
4 | * | |
5 | * This file is part of FFmpeg. | |
6 | * | |
7 | * FFmpeg is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU Lesser General Public | |
9 | * License as published by the Free Software Foundation; either | |
10 | * version 2.1 of the License, or (at your option) any later version. | |
11 | * | |
12 | * FFmpeg is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | * Lesser General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU Lesser General Public | |
18 | * License along with FFmpeg; if not, write to the Free Software | |
19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
20 | */ | |
21 | ||
22 | /** | |
23 | * @file | |
24 | * Common code between the AC-3 encoder and decoder. | |
25 | */ | |
26 | ||
27 | #ifndef AVCODEC_AC3_H | |
28 | #define AVCODEC_AC3_H | |
29 | ||
30 | #define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */ | |
31 | #define AC3_MAX_CHANNELS 7 /**< maximum number of channels, including coupling channel */ | |
32 | #define CPL_CH 0 /**< coupling channel index */ | |
33 | ||
34 | #define AC3_MAX_COEFS 256 | |
35 | #define AC3_BLOCK_SIZE 256 | |
36 | #define AC3_MAX_BLOCKS 6 | |
37 | #define AC3_FRAME_SIZE (AC3_MAX_BLOCKS * 256) | |
38 | #define AC3_WINDOW_SIZE (AC3_BLOCK_SIZE * 2) | |
39 | #define AC3_CRITICAL_BANDS 50 | |
40 | #define AC3_MAX_CPL_BANDS 18 | |
41 | ||
42 | #include "libavutil/opt.h" | |
43 | #include "avcodec.h" | |
44 | #include "ac3tab.h" | |
45 | ||
46 | /* exponent encoding strategy */ | |
47 | #define EXP_REUSE 0 | |
48 | #define EXP_NEW 1 | |
49 | ||
50 | #define EXP_D15 1 | |
51 | #define EXP_D25 2 | |
52 | #define EXP_D45 3 | |
53 | ||
54 | #ifndef USE_FIXED | |
55 | #define USE_FIXED 0 | |
56 | #endif | |
57 | ||
58 | #if USE_FIXED | |
59 | ||
60 | #define FFT_FLOAT 0 | |
61 | ||
62 | #define FIXR(a) ((int)((a) * 0 + 0.5)) | |
63 | #define FIXR12(a) ((int)((a) * 4096 + 0.5)) | |
64 | #define FIXR15(a) ((int)((a) * 32768 + 0.5)) | |
65 | #define ROUND15(x) ((x) + 16384) >> 15 | |
66 | ||
67 | #define AC3_RENAME(x) x ## _fixed | |
68 | #define AC3_NORM(norm) (1<<24)/(norm) | |
69 | #define AC3_MUL(a,b) ((((int64_t) (a)) * (b))>>12) | |
70 | #define AC3_RANGE(x) (x|((x&128)<<1)) | |
71 | #define AC3_HEAVY_RANGE(x) (x<<1) | |
72 | #define AC3_DYNAMIC_RANGE(x) (x) | |
73 | #define AC3_SPX_BLEND(x) (x) | |
74 | #define AC3_DYNAMIC_RANGE1 0 | |
75 | ||
76 | #define INTFLOAT int | |
77 | #define SHORTFLOAT int16_t | |
78 | ||
79 | #else /* USE_FIXED */ | |
80 | ||
81 | #define FIXR(x) ((float)(x)) | |
82 | #define FIXR12(x) ((float)(x)) | |
83 | #define FIXR15(x) ((float)(x)) | |
84 | #define ROUND15(x) (x) | |
85 | ||
86 | #define AC3_RENAME(x) x | |
87 | #define AC3_NORM(norm) (1.0f/(norm)) | |
88 | #define AC3_MUL(a,b) ((a) * (b)) | |
89 | #define AC3_RANGE(x) (dynamic_range_tab[(x)]) | |
90 | #define AC3_HEAVY_RANGE(x) (heavy_dynamic_range_tab[(x)]) | |
91 | #define AC3_DYNAMIC_RANGE(x) (powf(x, s->drc_scale)) | |
92 | #define AC3_SPX_BLEND(x) (x)* (1.0f/32) | |
93 | #define AC3_DYNAMIC_RANGE1 1.0f | |
94 | ||
95 | #define INTFLOAT float | |
96 | #define SHORTFLOAT float | |
97 | ||
98 | #endif /* USE_FIXED */ | |
99 | ||
100 | #define AC3_LEVEL(x) ROUND15((x) * FIXR15(0.7071067811865476)) | |
101 | ||
102 | /* pre-defined gain values */ | |
103 | #define LEVEL_PLUS_3DB 1.4142135623730950 | |
104 | #define LEVEL_PLUS_1POINT5DB 1.1892071150027209 | |
105 | #define LEVEL_MINUS_1POINT5DB 0.8408964152537145 | |
106 | #define LEVEL_MINUS_3DB 0.7071067811865476 | |
107 | #define LEVEL_MINUS_4POINT5DB 0.5946035575013605 | |
108 | #define LEVEL_MINUS_6DB 0.5000000000000000 | |
109 | #define LEVEL_MINUS_9DB 0.3535533905932738 | |
110 | #define LEVEL_ZERO 0.0000000000000000 | |
111 | #define LEVEL_ONE 1.0000000000000000 | |
112 | ||
113 | /** Delta bit allocation strategy */ | |
114 | typedef enum { | |
115 | DBA_REUSE = 0, | |
116 | DBA_NEW, | |
117 | DBA_NONE, | |
118 | DBA_RESERVED | |
119 | } AC3DeltaStrategy; | |
120 | ||
121 | /** Channel mode (audio coding mode) */ | |
122 | typedef enum { | |
123 | AC3_CHMODE_DUALMONO = 0, | |
124 | AC3_CHMODE_MONO, | |
125 | AC3_CHMODE_STEREO, | |
126 | AC3_CHMODE_3F, | |
127 | AC3_CHMODE_2F1R, | |
128 | AC3_CHMODE_3F1R, | |
129 | AC3_CHMODE_2F2R, | |
130 | AC3_CHMODE_3F2R | |
131 | } AC3ChannelMode; | |
132 | ||
133 | /** Dolby Surround mode */ | |
134 | typedef enum AC3DolbySurroundMode { | |
135 | AC3_DSURMOD_NOTINDICATED = 0, | |
136 | AC3_DSURMOD_OFF, | |
137 | AC3_DSURMOD_ON, | |
138 | AC3_DSURMOD_RESERVED | |
139 | } AC3DolbySurroundMode; | |
140 | ||
141 | /** Dolby Surround EX mode */ | |
142 | typedef enum AC3DolbySurroundEXMode { | |
143 | AC3_DSUREXMOD_NOTINDICATED = 0, | |
144 | AC3_DSUREXMOD_OFF, | |
145 | AC3_DSUREXMOD_ON, | |
146 | AC3_DSUREXMOD_PLIIZ | |
147 | } AC3DolbySurroundEXMode; | |
148 | ||
149 | /** Dolby Headphone mode */ | |
150 | typedef enum AC3DolbyHeadphoneMode { | |
151 | AC3_DHEADPHONMOD_NOTINDICATED = 0, | |
152 | AC3_DHEADPHONMOD_OFF, | |
153 | AC3_DHEADPHONMOD_ON, | |
154 | AC3_DHEADPHONMOD_RESERVED | |
155 | } AC3DolbyHeadphoneMode; | |
156 | ||
157 | /** Preferred Stereo Downmix mode */ | |
158 | typedef enum AC3PreferredStereoDownmixMode { | |
159 | AC3_DMIXMOD_NOTINDICATED = 0, | |
160 | AC3_DMIXMOD_LTRT, | |
161 | AC3_DMIXMOD_LORO, | |
162 | AC3_DMIXMOD_DPLII // reserved value in A/52, but used by encoders to indicate DPL2 | |
163 | } AC3PreferredStereoDownmixMode; | |
164 | ||
165 | typedef struct AC3BitAllocParameters { | |
166 | int sr_code; | |
167 | int sr_shift; | |
168 | int slow_gain, slow_decay, fast_decay, db_per_bit, floor; | |
169 | int cpl_fast_leak, cpl_slow_leak; | |
170 | } AC3BitAllocParameters; | |
171 | ||
172 | /** | |
173 | * @struct AC3HeaderInfo | |
174 | * Coded AC-3 header values up to the lfeon element, plus derived values. | |
175 | */ | |
176 | typedef struct AC3HeaderInfo { | |
177 | /** @name Coded elements | |
178 | * @{ | |
179 | */ | |
180 | uint16_t sync_word; | |
181 | uint16_t crc1; | |
182 | uint8_t sr_code; | |
183 | uint8_t bitstream_id; | |
184 | uint8_t bitstream_mode; | |
185 | uint8_t channel_mode; | |
186 | uint8_t lfe_on; | |
187 | uint8_t frame_type; | |
188 | int substreamid; ///< substream identification | |
189 | int center_mix_level; ///< Center mix level index | |
190 | int surround_mix_level; ///< Surround mix level index | |
191 | uint16_t channel_map; | |
192 | int num_blocks; ///< number of audio blocks | |
193 | #if AV_HAVE_INCOMPATIBLE_LIBAV_ABI | |
194 | int dolby_surround_mode; | |
195 | #endif | |
196 | /** @} */ | |
197 | ||
198 | /** @name Derived values | |
199 | * @{ | |
200 | */ | |
201 | uint8_t sr_shift; | |
202 | uint16_t sample_rate; | |
203 | uint32_t bit_rate; | |
204 | uint8_t channels; | |
205 | uint16_t frame_size; | |
206 | uint64_t channel_layout; | |
207 | /** @} */ | |
208 | #if !AV_HAVE_INCOMPATIBLE_LIBAV_ABI | |
209 | int dolby_surround_mode; | |
210 | #endif | |
211 | } AC3HeaderInfo; | |
212 | ||
213 | typedef enum { | |
214 | EAC3_FRAME_TYPE_INDEPENDENT = 0, | |
215 | EAC3_FRAME_TYPE_DEPENDENT, | |
216 | EAC3_FRAME_TYPE_AC3_CONVERT, | |
217 | EAC3_FRAME_TYPE_RESERVED | |
218 | } EAC3FrameType; | |
219 | ||
220 | void ff_ac3_common_init(void); | |
221 | ||
222 | /** | |
223 | * Calculate the log power-spectral density of the input signal. | |
224 | * This gives a rough estimate of signal power in the frequency domain by using | |
225 | * the spectral envelope (exponents). The psd is also separately grouped | |
226 | * into critical bands for use in the calculating the masking curve. | |
227 | * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters | |
228 | * determines the reference level. | |
229 | * | |
230 | * @param[in] exp frequency coefficient exponents | |
231 | * @param[in] start starting bin location | |
232 | * @param[in] end ending bin location | |
233 | * @param[out] psd signal power for each frequency bin | |
234 | * @param[out] band_psd signal power for each critical band | |
235 | */ | |
236 | void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, | |
237 | int16_t *band_psd); | |
238 | ||
239 | /** | |
240 | * Calculate the masking curve. | |
241 | * First, the excitation is calculated using parameters in s and the signal | |
242 | * power in each critical band. The excitation is compared with a predefined | |
243 | * hearing threshold table to produce the masking curve. If delta bit | |
244 | * allocation information is provided, it is used for adjusting the masking | |
245 | * curve, usually to give a closer match to a better psychoacoustic model. | |
246 | * | |
247 | * @param[in] s adjustable bit allocation parameters | |
248 | * @param[in] band_psd signal power for each critical band | |
249 | * @param[in] start starting bin location | |
250 | * @param[in] end ending bin location | |
251 | * @param[in] fast_gain fast gain (estimated signal-to-mask ratio) | |
252 | * @param[in] is_lfe whether or not the channel being processed is the LFE | |
253 | * @param[in] dba_mode delta bit allocation mode (none, reuse, or new) | |
254 | * @param[in] dba_nsegs number of delta segments | |
255 | * @param[in] dba_offsets location offsets for each segment | |
256 | * @param[in] dba_lengths length of each segment | |
257 | * @param[in] dba_values delta bit allocation for each segment | |
258 | * @param[out] mask calculated masking curve | |
259 | * @return returns 0 for success, non-zero for error | |
260 | */ | |
261 | int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, | |
262 | int start, int end, int fast_gain, int is_lfe, | |
263 | int dba_mode, int dba_nsegs, uint8_t *dba_offsets, | |
264 | uint8_t *dba_lengths, uint8_t *dba_values, | |
265 | int16_t *mask); | |
266 | ||
267 | #endif /* AVCODEC_AC3_H */ |